///<summary>
/// Find the previous occurence of the byte pattern. Works asynchronously.
///</summary>
public IAsyncResult FindPrevious(AsyncCallback ac)
{
if (dataBook.NPages == 0 || inUse)
{
FindPreviousOperation op = new FindPreviousOperation(strategy, null, FindAsyncCallback);
return(HandleProblematicOp(op, ac));
}
inUse = true;
userFindAsyncCallback = ac;
findFinishedEvent.Reset();
// if this is the first time we are checking
// for a valid pattern, emit the event
if (firstTime == true && strategy.Pattern.Length > 0)
{
firstTime = false;
if (FirstFind != null)
{
FirstFind();
}
} // is pattern acceptable?
else if (strategy.Pattern.Length == 0)
{
return(null);
}
DataView dv = ((DataViewDisplay)dataBook.CurrentPageWidget).View;
strategy.Buffer = dv.Buffer;
// decide where to start searching from
if (!dv.Selection.IsEmpty())
{
strategy.Position = dv.Selection.End;
}
else
{
strategy.Position = dv.CursorOffset;
}
SetUpFindProgressReport();
FindPreviousOperation fpo = new FindPreviousOperation(strategy, progressCallback, FindAsyncCallback);
// lock the buffer, so user can't modify it while
// searching
strategy.Buffer.ModifyAllowed = false;
strategy.Buffer.FileOperationsAllowed = false;
// start find thread
Thread findThread = new Thread(fpo.OperationThread);
findThread.IsBackground = true;
findThread.Start();
return(new ThreadedAsyncResult(fpo, findFinishedEvent, false));
}
void FindPreviousAsyncCallback(IAsyncResult ar)
{
ThreadedAsyncResult tar = (ThreadedAsyncResult)ar;
FindPreviousOperation state = (FindPreviousOperation)tar.AsyncState;
if (state.Result == FindPreviousOperation.OperationResult.Finished && state.Match == null)
{
InformationAlert ia = new InformationAlert(Catalog.GetString("The pattern you requested was not found."), Catalog.GetString("Beginning of file reached."), mainWindow);
ia.Run();
ia.Destroy();
}
}
